Control of Blood Flow & Poiseulle's Law*
 

  • "Poiseuille's law gives insight into the complex task of regulating blood flow to different parts of the body.

  •  In response to demand, the body must direct more oxygen and nutrients to one region of the body, and if necessary temporarily curtail the supply to a less essential region. 

  • Since the flow resistance depends upon the fourth power to the interior radius of a vessel, the processes of vasodilation and vasoconstriction offer powerful control mechanisms."

"If there is a need to increase the blood flow through a given vessel by percent, or to x its original value, then vasodilation by percent or to x its original radius will accomplish the increase. This assumes that the applied pressure remains the same."

"The effect of vessel radius is just as dramatic in reduction. A reduction the the interior radius of a vessel by percent or to x its original radius will reduce the flow by percent, or to x its original value."

*(courtesy of Dr. Rod Nave, Georgia State University) (http://hyperphysics.phys-astr.gsu.edu/hbase/hframe.html)